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[REBOL] Re: How do I dynamically extend an object! instance

From: g:santilli:tiscalinet:it at: 10-Sep-2000 18:34

Hello [bobr--dprc--net]! On 10-Set-00, you wrote: b> object-addword: func [ b> { add a word only if it is not already there, b> returns a new instance of the object b> examples b> myobj: object-addword myobj emailaddr b> dbrecord: object-addword/initial dbrecord areacode b> 978 b> } I'd suggest: object-addword: func [ object [object!] 'word [word!] /initial value [any-type!] ] [ either not found? in object word [ make object reduce [to-set-word word value] ] [ object ] ]
>> probe o
make object! [ a: 1 ]
>> probe object-addword o b
make object! [ a: 1 b: none ]
>> probe object-addword/initial o b 2
make object! [ a: 1 b: 2 ]
>> probe object-addword/initial o a 2
make object! [ a: 1 ] b> - can it be done without creating a new instance? I'm afraid not, with the current implemenation of REBOL. b> - can a corresponding function for removing a word b> from an object be written without evaluating b> all the other words/elements? I can only think of: remove-word: func [ object [object!] 'word [word!] /local words values ] [ if found? in object word [ words: first object values: second object object: clear [] foreach obj-word next words [ if obj-word <> word [insert object to-set-word obj-word] ] insert tail object none object: make object! object remove at values index? find words word set next bind first object in object 'self next values ] object ] HTH, Gabriele. -- Gabriele Santilli <[giesse--writeme--com]> - Amigan - REBOL programmer Amiga Group Italia sez. L'Aquila --